Membranous or diaphragm transmitter for submarine sound-signals



W. HAHNEMANN.

MEMBRANOUS 0H DIAPHRAGM TRANSMHTER FOR SUBMARINE SOUND SIGNALS.

APPLICATION FILED OCT. 8, 1915.

1,331,149. Patented Feb. 17,1920.

jzrcnior WALTER HAHNEMANN, OF KITZEBERG, NEAR KIEL, GERMANY.

MEMBRANOUS OR DIAPHRAGM TRANSMITTER FOR SUBMARINE SOUND-SIGNALS.

Specification of Letters Patent.

Patented Feb. 17, 1920.

Application filed October 8,-1915. Serial No. 54,793.

To all whom it may concern Be it known that I, WALTER HAI-INEMANN, engineer, a subjectof the German Emperor, and residing at Kitzeberg, near Kiel, county of Schleswig-Holstein, State of Prussia,

ermany, have invented certain new and useful Improvements in Membranous or Diaphragm Transmitters for Submarine Sound-Signals, of which the following is a specification.

The invention relates to a membranous or diaphragm transmitter for submarine sound signals constructed in such a manner as to transform the energy produced in the form of shocks, blows or in another aperiodic form into acoustic vibrations and to radiate said vibrations into the surrounding water.

Where a radiator that impinges on the water, for example a membrane like the outer skin of a ship, is to be used to transform the imparted mechanical energy of an energizer into acoustic vibrations and to radiate the vibrations into the water, the difliculty has arisen that by directly coupling the energizer with the radiator, on account of the very slight compressibility of the water and the resulting very small amplitudes of motion of the water molecules only a relatively small part of the exciting energy can, in the form of acoustic vibrations, be conveyed or transmitted to the water. Thus in order to excite a larger mass of water efl ectively, the exciting energy, for example conveyed in the form of shocks, must be so great that the radiator would be destroyed in a short time without obtaining a satisfactory sound transmitting effect. On the other hand, if a tunable system surrounded directly by water, for example a bell is rung, then the damping of radiation effected by the water is too much to permit a very effective or efiicient transformation of energy.

The present invention consists in introducing between the energizer and the radiating member that impinges on the water, an intermediate member by means of which the amplitudes of motion of the exciting energy may be transformed to a smaller value while the amplitudes of force are transformed to a greater value.

It is already known that in membranous or diaphragm transmitters the required amplitude ratio may be obtained by introducing a tunable vibratory system between the energizer and the radiator, but in transmitters of this kind always undamped electromagnetic excitation has hitherto only been used. The present invention offers the ad vantage that it makes it possible to cause the excitation by shocks, thus avoiding the necessity of adapting the driving means to the tuning of the vibratory system.

In contrast to the known submarine bells generally excited by shocks, the invention offers the advantage that by introducing a membrane between the vibratory system and the water, the damping of radiation of the vibratory system, which, as is known in the case of the usual bells arranged directly in the water, is much too high, can be exactly reduced to the most favorable amount.

In the accompanying drawing two illustrative embodiments of the invention are represented by way of example, the intermediate vibratory system being a tuning fork, which may be vibrated in different ways.

Figure 1 shows a form of the invention in which the tuning fork is set in vibration by means of a blow from a hammer-like arrangement.

Fig. 2 shows another form of the invention in which the tuning fork is set in vibration by means of blows from the projections of a cam wheel.

On both figures A is a membrane impinging on the water B and forming the radiator for the sound oscillations. The tuning fork C forms the transmission element, the stem D of .which, having the greatest amplitudes of force, is connected to the membrane, while the exciting energy is imparted to the prongs E, having the greatest amplitudes of motion.

In the form shown in Fig. 1 the tuning fork is excited by means of a hammer F, which may be driven in any manner, for example by electric remote control. In the form illustrated in Fig. 2 the prongs of the tuning fork are struck by means of a camwheel G the projecting lugs H H of which push against a head J disposed on one of the prongs. But the intermediate vibratory member may be excited also by means of a violin bow, or in any other suitable way.

The essential of the invention only consists in aperiodically exciting the vibratory system by means of a mechanical device acting on a point of greater amplitudes of motion of the vibratory system and in introducing between said vibratory system and the Water a membrane affected by a point of smaller amplitudes of the vibratory system.

What I claim is 1. A transmitter for submarine sound signals comprising a transmission element having points of different amplitudes of motion, means separate from said element for aperiodically applying physical force to said element at the points which have great amplitudes of motion, and a body impinging on the Water for transforming the produced energy into acoustic vibrations and connected With points of the transmission element having small amplitudes of motion.

2. A transmitter for submarine sound signals comprising a transmission element consisting of a tuning fork, a separate hammer adapted to aperiodically actuate a said tuning fork prong of said turning fork, and a body connected to the stem of said tuning fork and impinging on the Water to transmit the vibrations of said tuning fork to the water. 3. A transmitter for submarine sound signals comprising a transmission element consisting of a tuning fork, separate means adapted to aperiodioally strike a prong of the tuning fork, and a body connected to the stem of said tuning fork and impinging on the Water to transmit the vibrations of to the Water. In testimony whereof I aiiiX my signature in presence of tWo Witnesses.

v WALTER. HAHNEMANN.

Witnesses: v

J ULIUSRONKE, I BRUNO KAH E. 

